It might be nicknamed the red planet, but there's a lot more to Mars than just rocks and red dust. NASA's images show plenty of hidden beauty and intrigue.
We've been combing the archive to pick a selection of the best and most interesting images NASA has compiled.
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Mars might not be much to look at now, but that doesn't mean it isn't full of fascinating sights that tell tales about its history.
In ancient times, it's thought that water once ran on Mars, carving channels through the landscape and transporting sediment as it went. This image shows a spectral analysis from orbit which highlights chemical alteration in the surface caused by this water.
This image from Jezero Crater delta shows a surface that's rich in clay and carbonates. The landforms you can see are thought to date back over 3.6 billion years and are possibly home to ancient organic molecules and other potential signs of microbial life. This is why NASA has chosen this area as the landing site for the next Rover, that's set to land on the planet in 2020.
South Pole Spiders
Fear not, these are not giant alien spiders, but instead, are cracks on the surface of Mars. This was captured by the Mars Reconnaissance Orbiter in 2009 and shows a region of the South Pole of the red planet where cracks have appeared on the surface.
It is thought that these cracks have appeared as carbon dioxide has escaped from melting ice and dissipated into the atmosphere. We're just glad they aren't moving.
Dust and frost on the surface
In the middle of 2018, NASA's Mars Reconnaissance Orbiter captured images of sand dunes in the northern regions of Mars. These appeared to show light coloured coatings of dust blown across other darker sandy regions.
Close observation shows some patches of dry ice around the very edges of the dunes - patches that would quickly turn into gas during the summer season.
Another image from NASA's Mars Reconnaissance Orbiter shows an area of Mars with classic barchan dunes (crescent-shaped sand dunes). These dunes have collected inside the floor of the Lyot Crater.
One area of the dunes, when colour enhanced, appears to be a cool turquoise blue showing it to be made of a much finer material than the surrounding area.
Another image of the same area captured in 2017 shows some similarly weird and wonderful shapes in the crater.
This image from the north pole of Mars shows thick icy layers on the surface of the planet. It's not all just rocks and dust down there.
This image was captured by the Mars Reconnaissance Orbiter which picked up on the seasonal frost accumulating in that area.
This image of Mars is one of a series from the Northern Polar regions of the planet. This area shows a lot of change over the years and includes not only new ice blocks forming, but also sections of ice cliff collapsing. NASA has a fairly awesome view of that happening too.
This new image was captured by the Mars Reconnaissance Orbiter which was tasked with re-imaging regions of Mars that had been snapped years before in order to compare the landscape. Just like on Earth, a lot has changed over those years, even since the area was first imaged in 2006.
What collection of images of Mars would be complete without a selfie by a Mars rover? This shot of the Curiosity rover was taken in 2015. This image is actually a collection of images that at the "Mojave" site where the rover was busy drilling and collecting rock samples for analysis.
Other similar images of Curiosity busying itself with analysis of the landscape were captured at Rocknest, John Klein and Windjana. We love the idea of these rovers roaming the surface of the planet carrying out important tests on behalf of the whole of mankind.
Possible Methane sources
In 2018, the Mars Orbiter captured this image of the surfaces in the Chryse Planitia region of the planet close to the equator. The image shows large mounds, said to be hundreds of metres in size.
Scientists are not clear on what has caused these mounds, but think it may either be the result of lava eruptions or hot mud emerging from beneath the surface. If it is the latter, it may well point to signs of methane on Mars - something scientists have been looking for for a while.
Dunes near Nili Patera
This image from Nili Patera reveals some interesting insight into the weather of Mars. Dunes captured in the image show that winds on the surface continuously blow from east to west moving sand across the area.
Gradual sand movement is happening here, with dunes repositioning over time as the wind continues to move the sand around.
Layers of history
Many of these images are not only incredible views of the planet, but also offer scientific insight into the history of Mars that can be studied here on Earth:
"The geologic history of a planet is written in its layers. Erosion of the surface reveals several shades of light-toned layers, likely sedimentary deposits, as shown in this image taken by the HiRISE camera on the Mars Reconnaissance Orbiter. The most recent geologic features are the narrow sand dunes snaking across the top of all the rocks.
HiRISE operates in visible wavelengths, the same as human eyes, but with a telescopic lens that produces images at resolutions never before seen in planetary exploration missions. These high-resolution images enable scientists to distinguish 1-meter-size (about 3-foot-size) objects on Mars and to study the morphology (surface structure) in a much more comprehensive manner than ever before."
Tracks in the dust
Just like Earth, the surface of Mars is regularly subjected dust devils - well-formed and strong whirlwinds of varying size that whip up dirt on the surface.
This image shows long dark trails where these whirlwinds have passed and blown the dirt around. The darker lines show the material underneath the usual surface dirt and dust.
A wonderfully weird image of the surface of Mars known casually as the "brain terrain" - this is apparently one of the unsolved mysteries of the planet. This strange looking textured terrain is made up of ridge and troughs found across Mars.
It is thought that water buried below the surface is causing these weird and wonderful shapes as it sublimates (turns into a gas) and emerges from the land. More data is required to establish this as fact though.
Brain terrain again
Another view of the same area shows the strange weaving of the landscape and the similarity to the human brain is uncanny.
Eye on the storm
In the middle of 2018, the Hubble Space Telescope captured this image of Mars as it passed into the closest proximity to our home since 2003.
Visible in the image is a dust storm that has raged throughout the planet and covered the entirety of Mars into one giant dust cloud. Another highlight here is the two poles of the planet that are covered in a bright blanket of clouds.
The two bright dots that can be seen in the darkness of space surrounding the planet are Phobos and Deimos - the two moons that belong to Mars.
This image dates back to 2007 and shows the Russell Crater dune field. This area of Mars is often covered in carbon dioxide frost. When that frost evaporates, the area changes significantly. In the top of the image, patches of the remaining frost can be seen. The black markings are the rust of dust devils trailing across the surrounding landscape.
This image shows the southern hemisphere of Mars at the end of the summertime. The peaks of the mountain ranges here appear to be covered in ice and snow, but NASA says this isn't possible during this summer period and it's more likely to be mineral deposits instead.
This image from the Mars Reconnaissance Orbiter shows the Deuteronilus Mensae region of Mars. A lobe-shaped formation can be seen on the right side of the image. These formations are thought to be caused by icy regions of the land subliminating and dissipating.
This view shows some straight ridges in the ancient bedrock that makes up the surface of Mars near Nirgal Valles - one of the longest valleys on the planet.
It is thought this bedrock has hardened over time and has been able to withstand billions of years of erosion. An impressive feat for an intriguing view.
An amazing Mesa
Another incredible image from the surface of Mars shows a small Mesa that's surrounded by sand dunes. The area is heavily eroded and includes several sedimentary deposits within the Mesa. A beautiful view of the power of nature on Mars and how the planet reacts to the environment around it.
Saheki's secret layers
This view shows Saheki Crater - a crater that's around 84 kilometres across. This crater is filled with alluvial fans (triangle-shaped deposits) that were likely created when melting snow carried different materials down from the edge of the crater into the centre.
The result is a beautiful, colourful and intriguing bit of landscape of Mars brilliantly captured by the Mars Reconnaissance Orbiter.
Layers and dunes
Most of the surface of Mars is covered in dust, dirt and other materials that cover the bedrock below. This image shows one area of the planet where the bedrock is exposed to the elements. Here, layers of red bedrock can be seen with what looks like age rings.
The Hargraves Crater
This image from the Mars Reconnaissance Orbiter shows an area of Mars that's been hit by different space debris. A rich and varied bedrock surface in the area means coloruful minerals and materials have been spread across the surroundings. The result is a brilliantly colourful image of Mars unlike many others you're likely to see.
The surface of Mars is often changing thanks to hundreds of new asteroid impacts on the surface on a regular basis.
Mars has a much thinner atmosphere than Earth, meaning it's less protected than our planet when it comes to such interstellar dangers.
This image shows a brand new crater which was formed with explosive results as the blast sent debris in all directions. The exposed materials vary wild in colours and show a great variety of materials.
An unusual sight of a crater on the surface of Mars shows a view that looks slightly like a tadpole. The tail of this crater was likely created by water running out of the crater and flowing downhill.
This sort of image is useful for scientists who are trying to study the history of the area and how water existed and reacted with surroundings.
A shot of Meridiani Planum shows some interesting layered deposits and faults that have clean breaks too. Another fantastic view of the surface of Mars thanks to the Mars Reconnaissance Orbiter.
Another Curious view
This image shows the view from NASA's Curiosity Mars rover. Mount Sharp can be seen within Curiosity's eyeline and the rocky surface of Mars certainly looks formidable.